KR20050115182A - Method and apparatus for detecting time division multiplexing frame in a mobile communication system - Google Patents

Abstract

The present invention relates to a time division multiple frame detection method and apparatus, which are transmitted through a control channel of a mobile communication system that can easily detect time division multiple frames in a mobile communication system to improve reception reliability of a control channel. In the process of detecting whether the time-division multiple frames transmitted through the control channel shared by the mobile terminal of the first to perform a periodic append check on the received frame to output a first error detection bit (e1), and The received power PE [k] of the frame and the first path distance PM [k] during channel decoding are obtained. After estimating a second path distance FQM [k] using the first path distance PM [k] and the received power PE [k], the second path distance FQM [k] is estimated. Frame quality for detecting the validity of the received frame based on the first and second error detection bits (e1, e2) and outputting a second error detection bit (e2) by comparing the predetermined path distance threshold value. Generate and output bits. Therefore, according to the present invention, the reliability of the frame error determination is improved by considering the path distance and the received power of the received frame together with the general CRC check.

Description

METHOD AND APPARATUS FOR DETECTING TIME DIVISION MULTIPLEXING FRAME IN A MOBILE COMMUNICATION SYSTEM}

The present invention relates to a method and apparatus for receiving a control channel of a mobile communication system providing a packet data service, and particularly, to easily detect a time division multiplexing (TDM) frame in a code division multiple access mobile communication system. The present invention relates to a time division multiple frame detection method and apparatus transmitted through a control channel of a mobile communication system to improve reception reliability of a control channel.

In general, the mobile communication system has evolved from providing a voice service to providing a data communication. Such mobile communication systems are being developed to provide broadcast services together with various data services. The broadcast service is configured to transmit broadcast data on a frame basis in a TDM manner. This is because, in transmitting the broadcast data, when the TDM scheme is used, the reception end can selectively receive only the minimum frames to improve the reception efficiency.

In the 3GPP2 camp using the CDMA method as a form of providing such broadcasting service, various standardization works are being performed. Among the standardization works proposed by the 3GPP2 camp, CDMA2000 1x Rev. In the D protocol, a broadcast service is called a BCMCS (Broadcast Multicast Service). The CDMA2000 1x Rev. The D protocol stipulates the physical channel specification of the 1x EV-DV (Evolution for Data & Voice) system that provides packet service and voice service at the same time. Hereinafter, a control for transmitting control information to each user in the BCMCS service among the physical channels. A forward dedicated channel (F-DCCH), which is a channel, will be described.

That is, in the BCMCS service, unlike the unicast method, it is prescribed to transmit broadcast data of a broadcast method or push to talk (PTT) service data to a plurality of users using one physical channel. In the forward link of the 1x EV-DV system that provides the BCMCS service, control information is transmitted to a plurality of users using the forward designated channel (F-DCCH). In addition, the F-DCCH is shared by a plurality of users using a TDM scheme, and each user is identified by a long code mask as is well known.

FIG. 1 is a block diagram illustrating the structure of a transmitter 100 and a receiver 200 of a typical mobile communication system. Referring to FIG. 1, a forward designated channel used as a control channel based on a 1x EV-DV system ( The baseband physical channel specification of the F-DCCH and the structure of the receiver 200 will be described.

In FIG. 1, the CRC inserter 110 inserts a Cyclic Redundancy Checking (CRC) bit into the information bits for error checking of information bits transmitted as control information to a specific user and outputs them to the channel encoder 120. do. The channel encoder 120 performs channel coding on the information bits into which the CRC bit is inserted and outputs the scrambler 130. The channel coding is performed using, for example, well-known convolutional coding.

The scrambler 130 outputs to the spreader 140 by performing a long code mask scrambling process for each user to secure the channel-coded information bits. The spreader 140 spreads the encrypted information bits using a PN code and a Walsh code and then transmits the encrypted information bits to the wireless network. In this case, the spread information bits are transmitted to the receiver 200 through the above-described forward designation channel (F-DCCH) in units of frames.

The despreader 210 of the receiver 200 despreads the information bits of the received frame using the PN code and the Walsh code and outputs the decoded information bits to the descrambler 220. The descrambler 220 descrambles the despread information bits using a long code mask and outputs the decoded information bits to the channel decoder 230. The channel decoder 230 performs channel decoding on the received frame to decode the received bits. Decoded bits) are output to the CRC checker 240. In this case, the channel decoder 230 uses a well-known Viterbi decoder when the convolutional encoder is used as the channel encoder 120.

The CRC checker 240 checks whether a received frame has a transmission error by using the CRC bits included in the decoding bits, and checks an error detection bit for determining whether the received frame is valid, that is, whether the decoding bits are valid. Output

In the above 1x EV-DV system, a plurality of users share a Forward Specified Channel (F-DCCH) in which information bits, which are control information, are transmitted in a frame to support a broadcast service, using a TDM scheme. As described above, the user can distinguish using a long code mask.

FIG. 2 schematically illustrates a structure of a control channel through which control information is transmitted in a TDM scheme in a general mobile communication system, wherein the control channel uses the forward designated channel (F-DCCH). 2, user 3, etc.) are time-divided in frame units (T _F ), and the control information, that is, the information bits, is encrypted with a long code mask assigned to each user to distinguish the control information transmitted to each user. .

The receiving terminal 200 of FIG. 1 descrambles the encrypted information bits using a unique long code assigned to each mobile terminal. In this case, if the descrambled information bits belong to the TDM frame corresponding to the decoded information bits, the CRC checker 240 of the receiver 200 outputs an error detection bit having a good CRC result by maintaining the characteristic of a code word. However, in case of the TDM frame assigned to another user, the long code does not match and an error detection bit having a CRC result of "Bad" is outputted. If the reception quality of the frame is low, an error detection of a CRC result of "Bad" is also detected. By outputting the bit, the receiving end 200 can distinguish whether the received frame is a frame transmitted to itself.

As described above, when the long code and the CRC are used, each user may check whether each frame received through the control channel forward F-DCCH is a frame transmitted to the user. In practice, however, when a user of a frame transmitted through a control channel is distinguished using the above method, it is difficult to guarantee reception reliability.

CDMA 2000 1x Rev. Assuming that the information of the F-DCCH is transmitted using a frame length of 20 ms according to the D standard, for example, a 12-bit CRC is used to detect a frame error. In this case, in the case of a frame transmitted to another user, the signal after the long code descrambling at the receiving end is different from the code word due to the scrambling and descrambling by different long codes. Shows similar characteristics. Therefore, assuming that a received signal of another user's frame or a frame not including control information is output from the channel decoder 230 in the form of an arbitrary sequence, the false alarm probability (FAR) of the CRC check itself is approximately. 2.44 x 10 ^-4 , which means that on average, one detection error occurs every 82 seconds.

Therefore, when the service use time is relatively long, such as a broadcast service or a PTT service, it can be seen that the FAR of the CRC check is a very high value. In consideration of this, it can be seen that higher reception reliability must be ensured for the transmission signal of the F-DCCH in order to provide a stable service such as a broadcast service.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control channel of a mobile communication system that can easily detect a user-specific TDM frame transmitted through a control channel in a mobile communication system in which a plurality of users share a control channel. The present invention provides a method and apparatus for time division multiple frame detection transmitted through a PC.

A time division multiple frame detection method transmitted through a control channel of a mobile communication system according to the present invention for achieving the above object is a method of detecting a time division multiple frame transmitted through a control channel shared by a plurality of mobile terminals, the movement Receiving, by a terminal, the frame from a control channel, performing a periodic addition check on the received frame, outputting a first error detection bit, measuring a received power of the received frame, and Obtaining a first path distance during channel decoding of a received frame; estimating a second path distance using the first path distance and the received power; and calculating the second path distance and a predetermined path distance threshold value. Comparing a second error detection bit with the second error detection bit, and receiving the received error signal based on the first and second error detection bits. Including the step of generating and outputting a frame quality bits for detecting whether or not any valid feature a true.

An apparatus for detecting a time division multiple frame transmitted through a control channel in a mobile communication system according to the present invention for achieving the above object is the apparatus for detecting a time division multiple frame transmitted through a control channel shared by a plurality of mobile terminals. And a channel decoder for decoding a channel and obtaining a first path distance during channel decoding of the frame, and performing a cyclic addition test (CRC) on the decoding bits output from the channel decoder to detect a first error detection bit. A CRC checker for outputting, a reception power meter for measuring the received power of the frame, a path distance estimator for estimating a second path distance using the first path distance and the received power of the frame, and the second path distance A comparator for comparing a predetermined path distance threshold with a second error detection bit and outputting a second error detection bit; And a frame quality bit generator for generating and outputting frame quality bits for detecting the validity of the received frame based on the first and second error detection bits.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

Hereinafter, the basic concept of the present invention will be described prior to the description of the present embodiment.

First, in the present invention, in the process of detecting a transmission error of a TDM frame carrying information bits for each user, a new path considering both a received power of a frame and a path metric (hereinafter, referred to as a "first path distance") The distance (hereinafter referred to as "second path distance") is estimated. Then, the validity of the received frame is determined by comparing the second path distance with a preset predetermined path distance threshold.

According to the present invention, an error detection bit (hereinafter referred to as a "first error detection bit") according to a CRC check result of a channel decoded reception frame and an error detection bit according to the validity determination of a reception frame using the second path distance (Hereinafter referred to as " second error detection bit ") and when both the first and second error detection bits are determined to be valid, it is confirmed that the frame is normally received through the control channel.

Hereinafter, in order to help understanding of the present invention performing the above operation, a method of detecting a reception error of a frame using only the reception power of the frame and a reception error of the frame using only a path metric of the frame are described. After explaining the detection method, respectively, the method proposed by the present invention will be described.

FIG. 3A illustrates a method of determining whether a frame has a reception error using only received power of time-division multiple frames in a mobile communication system to which the present invention is applied. In FIG. 3A, a dotted line indicates control information transmitted to a user. Denotes frames 310 and 320, and the portion indicated by a solid line indicates a frame 330 (hereinafter, referred to as an "empty frame") that does not include control information. In this case, the frame including the control information is a frame 310 (hereinafter referred to as a "desired frame") transmitted to itself and a frame 320 (hereinafter referred to as a "second frame") transmitted to another user. undesired frame).

FIG. 3A illustrates a probability density function (PDF) for received power of each of the first to third frames 310, 320, and 330. However, in FIG. 3A, when the reception power of the first frame 310 transmitted to the user and the second frame 320 transmitted to the other user are similar to each other, it is difficult to distinguish between them.

FIG. 3B illustrates a method of determining whether a received frame is abnormal by using only path distances of time division multiple frames in a mobile communication system to which the present invention is applied. FIG. 3B illustrates the first to third frames 310 and 320. 330 shows the probability density function (PDF) for each path distance.

The path distance means a maximum value (hereinafter referred to as "maximum correlation value") among the correlation values between the bit string of the received frame and the code word or the bit string of the received frame. It means the minimum of Euclidean distances between codewords or the minimum of squared Euclidean distances (hereinafter referred to as "minimum Euclidean distance" or "minimum Euclidean distance square"). 3B illustrates an example of using the maximum correlation value as the path distance.

The path distance is obtained from the output of a Viterbi decoder used as a channel decoder at the receiving end. That is, when looking at the probability density function (PDF) of the path distance obtained from the output of the Viterbi decoder, when the second frame 320 of another user is received, the receiving end is descrambled by different long codes. The input signal of the decoder is converted into a form different from the codeword format. Therefore, the second frame 320 of another user may distinguish the first frame 310 of the user by displaying similar characteristics to the third frame 330 not including the control information.

However, as shown in FIG. 4, since the first to third frames 310, 320, and 330 transmitted to the TDM are power controlled and transmitted to a specific terminal, the received power of each frame of the terminal varies greatly. Accordingly, when only the path distance of the frame is used as shown in FIG. 3B, a variation may occur in the path distance of the second frame 320 transmitted to other users, thereby causing an error in the classification of each frame 310, 320, 330. .

As described above, since the frame error detection method using only the received power of the frame or the frame error detection method using only the path distance does not provide a stable result, it may be difficult to apply the additional frame reliability check after the CRC check. In the present invention, in order to solve such a problem, the above-described two methods are combined, but the first path distance and the received power are combined by using the ratio of the first path distance between the received frame and the codeword and the received power value of the frame. Proposes a characteristic equation to consider, compares the second path distance obtained from the characteristic expression with a predetermined predetermined path distance threshold value to determine whether the received frame is valid, and the above-described frame error detection method and general CRC check. In consideration of this, the reliability of the frame error determination is guaranteed.

That is, FIG. 5 is a block diagram illustrating an internal configuration of a time division multiple frame detection apparatus of a mobile communication system according to the present invention. The apparatus of FIG. ) Is used as a control channel, and the validity of the frame received from the control channel is determined according to the frame error detection method of the present invention.

In FIG. 5, the channel decoder 510 may determine a bit string of a frame received from a wireless network, that is, an input signal (Y [n]: n = 1, 2, ..., N, where N is the number of symbols in a frame period). The channel is decoded and the decoded bits are output to the CRC checker 520. The channel decoder 510 uses a well-known Viterbi decoder when the convolutional encoder is used as the channel encoder of the transmitter. The CRC checker 520 checks whether a frame has a reception error using the CRC bits included in the decoding bits, and outputs a first error detection bit e1 as a result of the check.

The channel decoder 510 has a predetermined code word set for obtaining a first path distance therein, obtains a maximum correlation value between the bit string of the received frame and the code word set, and calculates the correlation distance. The first path distance PM [k] is output. In addition, the channel decoder 510 obtains the minimum Euclidean distance or the minimum Euclidean distance square between the bit string of the received frame and the codeword set, and outputs the square of the Euclidean distance as the first path distance PM [k]. It is possible. Here, the channel decoder 510 outputs codewords obtained by obtaining a maximum correlation value as decoded bits.

Meanwhile, in FIG. 5, the reception power meter 530 measures the reception power PE [k] of the corresponding frame from the input signal Y [n] and outputs the received power PE [k] to the path distance estimator 540. FIG. 6 is a block diagram illustrating an internal configuration of the reception power meter 530. The reception power meter 530 performs an operation 531 of taking an m power of an absolute value with respect to the input signal Y [n] by one frame. Accumulated during the interval (533, 535) and outputs the accumulated value as the received power (PE [k]) of the frame. Here, n refers to a symbol index and k refers to a frame index. On the other hand, the order of m is basically 1, since the first path distance PM [k] output from the channel decoder 510 can be expressed as a linear combination of the input signal Y [n]. .

In FIG. 5, the path distance estimator 540 receives the first path distance PM [k] calculated from the channel decoder 510 and the received power PE of the frame calculated from the received power meter PE [k]. A second path distance FQM [k] for determining whether a received frame is valid is estimated by using a rational relationship between [k]). The second path distance FQM [k] is divided and estimated in two ways according to the algorithm for obtaining the path distance. In addition, the present invention proposes two characteristic formulas defining the rational relationship, and a detailed description of the characteristic formula will be described later.

Therefore, in the present invention, it should be noted that the second path distance FQM [k] may be obtained in various patterns as many as (number of algorithms for calculating path distance x number of characteristic expressions). In the present embodiment, the algorithm for calculating the path distance uses a method of using the maximum correlation value or the minimum Euclidean distance or the minimum Euclidean distance square between the bit string and the codeword set of the received frame as described above. A basic principle of estimating the second path distance FQM [k] according to the scheme will be described.

When the first path distance PM [k] is obtained by using the maximum correlation value as the first method of estimating the second path distance FQM [k], when a frame allocated to itself is decoded, a relatively large path When the distance is obtained and the frame containing only the noise component is decoded because no control information is included, a small path distance is obtained. When restoring a frame assigned to another user, a relatively small path distance is obtained. At this time, the path distance is characterized by being proportional to the received power of the frame.

Therefore, in case of the first method, the frame allocated to the user will have a larger path distance than the received power, and the frame assigned to another user will have a smaller path distance than the received power. The second path distance FQM [k] is estimated.

In the second method of estimating the second path distance FQM [k], the first path distance PM [k] is obtained by using the minimum Euclidean distance or the minimum Euclidean distance square. When the frame is decoded, a relatively small path distance is obtained. When the frame is decoded without the control information and only a noise component is present, a large path distance is obtained. When a frame allocated to another user is restored, a relatively large path distance is obtained. At this time, the path distance is inversely proportional to the received power of the frame.

Therefore, in case of the second method, the frame allocated to itself has a small path distance compared to the received power, and the frame allocated to another user will have a large path distance compared to the received power. The second path distance FQM [k] is estimated.

Meanwhile, in the present invention, when using a Viterbi decoder as a channel decoder that outputs a maximum correlation value, a characteristic formula defining a ratio relationship between the first path distance PM [k] and the received power PE [k] is given by the following < It is defined as Equation 1 or Equation 2, and the path distance estimator 540 of FIG. 5 is operated by using one of these characteristics.

Equation 1 represents a ratio of the first path distance PM [k] output from the channel decoder 510 and the received power PE [k] output from the reception power meter 530 to the second path distance. (FQM [k]).

Equation 2 is used to estimate the difference between the first path distance PM [k] and the received power PE [k] multiplied by the weight α as the second path distance FQM [k]. will be. In Equation 2, a performance of distinguishing one's frame from another user's frame is determined according to a change in the weight value α. According to the applicant's experiment, when the value α has a value of approximately 0.06, It can be seen that the classification performance. The value of α is not limited to the value exemplified above, and it is possible to use a value appropriately changed in consideration of the type of mobile communication system or the change in the communication environment.

On the other hand, when comparing the frame division performance of the second path distance estimated by Equation 1 and Equation 2, the fading channel and the terminal position compared to Equation 2 in the case of Equation 1 It has the advantage of not reacting sensitively. In the case of Equation 2, it is preferable to use an appropriate estimation method in consideration of a communication environment because the distinguishing performance of frames is superior to that of Equation 1.

The second path distance FQM [k] estimated in the above-described manner is transmitted to the comparator 550, and the comparator 550 is predetermined with the second path distance FQM [k]. The second error detection bit e2 that compares the value and determines whether the received frame is valid is output.

Here, when the second path distance is larger than the threshold value when the first path distance is estimated using the maximum correlation value, the comparator 550 determines a second error detection bit (e2) as a valid frame. ) Conversely, if the second path distance is less than the threshold value, the second error detection bit e2 that determines the received frame as the frame in which an error has occurred is output.

On the other hand, when the channel decoder 510 estimates the first path distance using the minimum Euclidean distance or the minimum Euclidean distance square, Equation 1 used in the path distance estimator 540 of FIG. And <Equation 2> is changed to the following <Equation 3> and <Equation 4>.

In Equations 3 and 4, the value of the weight β is determined by experimentally obtaining an appropriate value. Here, when the second path distance is less than the threshold, the comparator 550 outputs a second error detection bit e2 that determines a received frame as a valid frame, and the second path distance is the threshold. If greater, output a second error detection bit e2 that determines the received frame as a frame in which an error has occurred.

In addition, the equation for obtaining the second path distance by using Equations 3 and 4 may be in the form of Equation 5 and Equation 6, in which case, the second path distance. Is greater than the threshold, outputting a second error detection bit e2 that determines the received frame as a valid frame. Conversely, if the second path distance is less than the threshold value, the second error detection bit e2 that determines the received frame as the frame in which an error has occurred is output.

In Equations 5 and 6, the value of the weight γ is determined by experimentally obtaining an appropriate value. The frame quality bit generator 560 of FIG. 5 receives the first error detection bit e1 output from the CRC checker 520 and the second error detection bit e2 output from the comparator 550, respectively. After that, a predetermined frame quality bit is finally outputted to finally determine whether the received frame is valid. The frame quality bit generator 560 finally determines that the received frame is valid only if both of the results of the first and second error detection bits e1 and e2 determine that the received frame is valid, otherwise the received frame is received. Outputs a frame quality bit indicating that there is an error.

On the other hand, when the first error detection bit e1 of the CRC checker 520 is first outputted to the frame quality bit generator 560, and the result of the first error detection bit e1 indicates that there is an error in the received frame. It may be desirable to configure the apparatus of FIG. 5 so that the output process of the second error detection bit e2 is omitted. In this case, although not shown in FIG. 5, the frame quality bit generator 560 or a separate control unit controls the channel decoder 510 and the reception power meter 530 based on the result of the first error detection bit e1. It may also be desirable to selectively output two error detection bits e2.

According to the above configuration, it is possible to ensure the reliability of the frame error determination by considering the path distance and the received power of the received frame together with the general CRC check. In addition, the TDM frame detection method can be generally applied not only to receiving a F-DCCH but also to a physical channel transmitting data in a TDM format to a plurality of users using one physical channel. Care must be taken.

FIG. 7 is a flowchart illustrating a time division multiple frame detection method of a mobile communication system according to the present invention. Hereinafter, the method of the present invention will be described with reference to the configuration of FIG. 5.

First, in step 701, the channel decoder 510 performs channel decoding on the received frame, outputs the decoding bits to the CRC checker 520, and the CRC checker 520 transmits the CRCs included in the frame in the transmission process from the decoding bits. The first error detection bit e1, which extracts and examines the bit and determines whether the received frame is valid, is passed to the frame quality bit generator 580.

In step 703, the frame quality bit generator 580 reads the first error detection bit e1 according to the CRC check to determine whether the received frame is valid or an error frame. According to the procedure, it is determined that the decoding bits of the corresponding frame output from the channel decoder 510 are invalid, and the result is transmitted to an upper stage (not shown).

On the other hand, if it is determined in step 703 that the received frame is a valid frame, the frame quality bit generator 560 waits for the output of the second error detection bit e2 from the comparator 550. Accordingly, in step 707, the reception power measuring unit 530 takes an absolute value of the bit string of the reception frame, that is, the input signal Y [n], and then accumulates an operation taking m powers for one frame period to receive the corresponding frame. The power PM [k] is obtained and then transmitted to the path distance estimator 540.

At the same time, according to step 709, the channel decoder 510 obtains a maximum correlation value, minimum Euclidean distance, or minimum Euclidean distance square between a bit string of a received frame and a set of codewords provided therein, and calculates a first path distance (PM [ k]) to the path distance estimator 540. The path distance estimator 540 defines a proportional relationship between the first path distance PM [k] transmitted from the channel decoder 510 and the received power PM [k] transmitted from the reception power meter 530. The second path distance FQM [k] is estimated by using one of Equations 1 to 6 and output to the comparator 550.

 Thereafter, in step 711, the comparator 550 compares the second path distance FQM [k] transmitted from the path distance estimator 540 with a predetermined path distance threshold to determine whether the second path distance is within an effective range. Outputs a second error detection bit e2 that determines whether the received frame is a valid frame. At this time, it should be noted that the comparison process of the path distance threshold value should be performed in a different form depending on whether the maximum correlation value method or the minimum Euclidean distance / minimum Euclidean distance square method is used as described above.

That is, when the maximum correlation value method is used when comparing the path distance thresholds in step 711, the comparator 550 has a second path distance FQM [k] of <Equation 1> or <Equation 2> than the threshold value. If it is large, it is determined that the reception frame is valid, and if the minimum Euclidean distance method or the minimum Euclidean distance square method is used, the second path distance FQM [k] of Equation 3 or 4 is If it is smaller than the threshold, it is determined that the received frame is valid. Also, when the minimum Euclidean distance method or the minimum Euclidean distance square method is used, if the second path distance FQM [k] of Equation 5 or 6 is used, the second path distance is If it is larger than the threshold, it is determined that the received frame is valid.

Meanwhile, in the above-described embodiment, when the second path distance is obtained by taking the inverse of Equations 1 to 6, the operation of comparing the received frame and the path distance threshold in the comparator 550 is also performed inversely. . For example, in the above-described embodiment, when the second path distance is larger than the path distance threshold in Equation 2, the comparator 550 determines that the received frame is a valid frame, but takes the inverse of Equation 2 to obtain a second inverse. When obtaining the path distance, the comparator 550 determines that the received frame is a valid frame when the second path distance is smaller than the path distance threshold.

The frame quality bit generator 560 of FIG. 5 receives the first error detection bit e1 transmitted from the CRC checker 520 and the second error detection bit e2 transmitted from the comparator 550, respectively. If both error detection bits are found to have determined that the received frame is valid, in step 713, a frame quality bit that finally determines the output of the received frame, that is, the channel decoder, is generated and transmitted to the upper end.

On the contrary, if it is determined in step 711 that the second path distance FQM [k] falls within an error range as a result of the comparison of the path distance threshold value, the second error detection bit e2 indicating this is determined by the frame quality bit generator 560. The frame quality bit generator 560 generates and delivers a frame quality bit that finally determines that the received frame, that is, the output of the channel decoder, is invalid.

Hereinafter, the performance test results of the time division multiple frame detection method according to the present invention in the control channel will be described with reference to FIGS. 8 to 10.

8 to 10 show an example of using a maximum correlation value as a path metric, and the first frame allocated to itself in FIGS. 8 to 10 is denoted by reference numerals (A) and (F). The second frame assigned to another user is indicated by reference numerals (C) to (F) and (H) to (J), and the third frame without control information is indicated by reference numerals (B) and ( Each of them is indicated by G). (A) and (b) of FIGS. 8 to 10 respectively show a point (a) where the geometry of the mobile terminal is Ior / Ioc = 0 dB and a point (b) moved by Ior / Ioc = 8 dB, respectively. PDFs of path distances output from the channel decoder are shown.

First, FIG. 8 is a waveform diagram illustrating a performance test result of a time division multiple frame detection method using only a general path distance for comparison with the present invention. Referring to FIG. 8, since a mobile terminal is in a power control state, it is assigned to another user. The path distance value for the second frame [(C)-(E), (H)-(J)] is not clearly distinguished from the path distance value of the first frame [(A), (F)] assigned to it. It can be seen that.

9 is a waveform diagram illustrating a performance test result of a time division multiple frame detection method according to an embodiment of the present invention, which shows a result of estimating a second path distance using Equation 1 above. In the case of the second frames [(C) to (E), (H) to (J)] allocated to other users in FIG. 9, the second frames [(B) and (G)] that do not include control information are smaller than Since the path distance is obtained, the frame detection performance is greatly improved. In addition, it can be seen that the frame can be distinguished without a large influence according to the position of the mobile terminal, and thus it can be expected that the FAR, which is a rate at which an error occurs in a state where the CRC result is 'Good', can be sufficiently reduced.

FIG. 10 is a waveform diagram illustrating a performance test result of a time division multiple frame detection method according to another embodiment of the present invention, which shows a result of estimating a second path distance using Equation 2 above. In the case of the second frames [(C) to (E), (H) to (J)] allocated to other users in FIG. 10, similarly to the third frames [(B) and (G)] without control information. Since the path distance has a small value, it can be seen that the frame detection performance is greatly improved. In the case of FIG. 10, the position of the mobile terminal is somewhat influenced, but it can be seen that the frame can be sufficiently distinguished. Therefore, it can be expected that the FAR, which is the rate at which an error occurs in the state where the CRC result is 'Good', can be sufficiently reduced. have.

9 and 10, it can be seen that the case of Equation 1 is more stable than the case of Equation 2 with respect to the change of position of the mobile terminal. In the case of>, since the distinguishing performance of the first frame and the third frame is excellent, it can be seen that in the case of <Equation 1>, more stable performance is provided for the terminal whose position is determined.

As described above, according to the present invention, the reception reliability of the control channel can be improved by easily detecting a user-specific TDM frame transmitted through the control channel in a mobile communication system providing a broadcast service.

In addition, the present invention is to stably detect the TDM frame for each user transmitted through the control channel even for the position change of the terminal, and to reduce the system burden by preventing unnecessary changes and retransmission requests of the control information as the frame is stably received. Of course, the overall cell throughput can be improved.

1 is a block diagram showing the structure of a transmitter and a receiver in a general mobile communication system

2 is a diagram schematically illustrating a control channel structure in which control information is transmitted in a time division multiplexing scheme in a general mobile communication system;

FIG. 3A is a diagram for describing a method of determining whether a frame has a reception error using only received power of time division multiple frames in a mobile communication system to which the present invention is applied; FIG.

3B is a view for explaining a method of determining whether an abnormality of a reception frame is performed using only path distances of time division multiple frames in a mobile communication system to which the present invention is applied.

4 is a diagram illustrating an example in which received power of time division multiple frames is changed by power control in a mobile communication system to which the present invention is applied.

5 is a block diagram showing an internal configuration of a time division multiple frame detection apparatus of a mobile communication system according to the present invention.

6 is a block diagram illustrating an internal configuration of a reception power meter shown in FIG. 5.

7 is a flowchart illustrating a time division multiple frame detection method of a mobile communication system according to the present invention.

8 is a waveform diagram illustrating a performance test result of a general time division multiple frame detection method.

9 and 10 are waveform diagrams for explaining the performance test results of the time division multiple frame detection method according to the present invention

Claims (14)

A method for detecting time division multiple frames transmitted through a control channel shared by a plurality of mobile terminals, Receiving, by the mobile terminal, the frame from a control channel; Performing a periodic append check on the received frame to output a first error detection bit; Measuring a received power of the received frame; Obtaining a first path distance during channel decoding of the received frame; Estimating a second path distance using the first path distance and the received power; Outputting a second error detection bit by comparing the second path distance with a predetermined path distance threshold; And generating and outputting frame quality bits for detecting the validity of the received frame based on the first and second error detection bits. The method of claim 1, And the second path distance is estimated using a difference value between the first path distance and the received power. The method of claim 1, And the second path distance is estimated using a ratio relationship between the first path distance and received power. The method of claim 1, Wherein the first and second path distances are maximum correlation values. The method of claim 4, wherein The second error detection bit is determined to indicate the received frame as a valid frame if the second path distance is greater than the path distance threshold. The method of claim 1, Wherein the first and second path distances are minimum Euclidean distances. The method of claim 6, The second error detection bit is determined to indicate the received frame as a valid frame if the second path distance is less than the path distance threshold. The method of claim 1, When the first path distance is PM [k], the received power is PE [k], and the second path distance is FQM [k], the second path distance is further defined by Equation 1 below. The method characterized in that. [Equation 1] The method of claim 1, When the first path distance is PM [k], the received power is PE [k], and the second path distance is FQM [k], the second path distance is further defined by Equation 2 below. The method characterized in that. [Equation 2] The method of claim 1, And if at least one of the first and second error detection bits indicates an error occurrence of the received frame, the frame quality bit is determined to indicate the error occurrence. An apparatus for detecting a time division multiple frame transmitted through a control channel shared by a plurality of mobile terminals, A channel decoder configured to receive the frame and to decode the channel, and to obtain a first path distance during channel decoding of the frame; A CRC checker for outputting a first error detection bit by performing a periodic append check (CRC) on the decoding bits output from the channel decoder; A reception power meter for measuring reception power of the frame; A path distance estimator for estimating a second path distance using the first path distance and the received power of the frame; A comparator for comparing the second path distance with a predetermined path distance threshold and outputting a second error detection bit; And a frame quality bit generator for generating and outputting frame quality bits for detecting the validity of the received frame based on the first and second error detection bits. The method of claim 11, The frame quality bit generator is configured to indicate the error occurrence to the frame quality bit when at least one of the first and second error detection bits indicates an error occurrence of the frame. The method of claim 11, And the second path distance is estimated using a difference value between the first path distance and the received power. The method of claim 11, And the second path distance is estimated using a ratio relationship between the first path distance and received power.